Extended Calculations of Atomic Structure Parameters for Na-like Ar, Kr and Xe Ions Using Relativistic MCDHF and MBPT Methods (original) (raw)
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Multi-Configuration Dirac–Hartree–Fock (MCDHF) Calculations for B-Like Ions
Atoms, 2016
Relativistic configuration interaction results are presented for several B-like ions (Ge XXVIII, Rb XXXIII, Sr XXXIV, Ru XL, Sn XLVI, and Ba LII) using the multi-configuration Dirac-Hartree-Fock (MCDHF) method. The calculations are carried out in the active space approximation with the inclusion of the Breit interaction, the finite nuclear size effect, and quantum electrodynamic corrections. Results for fine structure energy levels for 1s 2 2s 2 2p and 2s2p 2 configurations relative to the ground state are reported. The transition wavelengths, transition probabilities, line strengths, and absorption oscillator strengths for 2s 2 2p-2s2p 2 electric dipole (E1) transitions are calculated. Both valence and core-valence correlation effects were accounted for through single-double multireference (SD-MR) expansions to increasing sets of active orbitals. Comparisons are made with the available data and good agreement is achieved. The values calculated using core-valence correlation are found to be very close to other theoretical and experimental values. The behavior of oscillator strengths as a function of nuclear charge is studied. We believe that our results can guide experimentalists in identifying the fine-structure levels in their future work.
Physica Scripta, 1992
We have calculated relativistic energies, weighted oscillator strengths and transition probabilities for electric dipole (E1) transitions among the terms belonging to 1snl (np9, lp3) configurations in helium-like sulphur. The calculations are based upon the multiconfiguration Hartree-Fock method within the framework of Breit-Pauli relativistic corrections. Our calculated values are also compared with other experimental and theoretical results. r the wavelengths and relative intensities of the intercombination lines 3 3 P 1 -1 1 S 0 in the spectra of laserproduced plasma. Lin et al. calculated oscillator strengths for the transitions m 3,1 S 0,1 -n 3,1 P 1 (3pm, np5). Mewe and Schrijver [16] evaluated line intensities of all lines for helium-like ions. Drake presented frequencies and transition rates in some helium-like ions. Berry et al. analyzed wavelengths and fine structure of 2s-2p transition in two-electron ions and compared them with theory and experiments. The wavelengths of 2 3 S-2 3 P transitions in S XV were measured by Livingston et al. . Precision wavelength measurements for 2 3 S 1 -2 3 P 0,2 transitions and 2 1 P 1 -1 1 S 0 and 2 3 P 1 -1 1 S 0 transition in helium-like sulphur were presented by DeSerio et al. [20] and Schleinkofer et al. . Energy levels for 1snl (n ¼ 2-5) states were calculated the perturbation method by power series in 1/Z and aZ by Vainshtein and Safronova . A theoretical study of two-photon emission rates for the 2 1 S state and n ¼ 1 and 2 states were presented by Drake . A comparison between calculated and measured wavelengths of resonance transitions were reported by Aglitsky et al. . The energies of the n ¼ 2 triplet states in helium-like ions were calculated with relativistic many-body perturbation theory by Johnson and Sapirstein [26]. Berry et al. [27] made a careful comparison of the triplet state energies. The results for relativistic configuration-interaction calculations of n ¼ 2 triplet states of helium-like ions were presented by Chen et al. [28]. Relativistic many-body calculations of n ¼ 1 and 2 states were observed by Plante et al. [29]. The list of wavelengths, oscillator strengths and statistical weights for spectral lines arising from the ground state were presented by Verner et al. [30]. Howie et al. [31] measured the wavelengths using photographic spectroscopy of beam foil n ¼ 2 triplet states. Kato et al. [32] reported theoretical atomic data of satellite spectra for helium-like sulphur with different methods. Two-photon decay rates of metastable 2 1 S 0 and 2 3 S 1 states were presented for helium-like ions in the Z ¼ 2-100 range by Derevianko and Johnson [33]. Safronova and Johnson [34] studied energy levels and autoionizing rates of some levels for helium-like with Z ¼ 4-54 ions. Kimura et al. [35] calculated rate coefficients for electron impulse excitation of helium-like ions with the Dirac R-matrix approach. Kingston et al. [36] obtained spontaneous transition rates for E1, M1, E2 and M2 transitions using fully relativistic GRASP and CIV3 codes.
Radiation Physics and Chemistry, 2020
We have systematically enlarged Multiconfiguration Dirac-Fock wavefunctions for the relativistic configuration interaction calculation to include the Breit interaction and quantum electrodynamic corrections for evaluating fine structure data of He-like ions having non-zero nuclear spin for five 3d group elements Scandium, Vanadium, Manganese, Cobalt and Copper. Computed energy levels, transition probabilities, oscillator strengths and x-ray wavelengths are compared with the available experimental values and theoretical computations. Special emphasis is given on the forbidden transition rates and hyperfine structure calculations as they are of potential interest in astrophysics. An attempt is made to study the individual contributions of the relativistic effects through Breit interaction and the quantum electrodynamic corrections such as vacuum polarization and self-energy correction to the line strengths useful for plasma diagnostic studies relevant to astrophysics.
Calculation of relativistic atomic transition and ionization properties for highly-charged ions
Physica Scripta, 1999
Recent years have seen a growing number of large^scale atomic structure calculations using both nonrelativistic and relativistic theories. For investigations of multiple and highly charged ions, of course, a relativistic structure code like the widely known GRASP program is required. In a revised version of this program, namely GRASP92 [F.A. Parpia, C.F. Fischer, and I.P. Grant, Comput. Phys. Commun. 94, 249 (1996)], systematic studies of level energies and a few other bound^state properties are now being supported. ö Here, we brie£y introduce a new package RATIP which extends GRASP92 towards the computation of various Relativistic Atomic Transition and Ionization Properties. A short overview of the capabilities of RATIP along with current developments will be given.
Indian Journal of Physics, 2019
Energies, weighted oscillator strengths (gf), line strengths (S) and radiative rates (A) for allowed and forbidden transitions are presented for 2s2p 6 2 S 1/2-2s 2 2p 5 2 P 1/2 , 2 P 3/2 and 2s 2 2p 5 2 P 1/2-2s 2 2p 5 2 P 3/2 transitions in fluorine-like Ca XII (Z = 20), Ti XIV (Z = 22), Cr XVI (Z = 24), Fe XVIII (Z = 26) and Ni XX (Z = 28) ions. Moreover, the allowed electric dipole (E1) and the forbidden electric quadrupole (E2), octupole (E3), magnetic dipole (M1) and quadrupole (M2) transition rates for some transitions are obtained. The 2s 2 2p 5-2s 2p 6-type transitions of F-like ions are prominent in hightemperature plasmas and are useful for diagnostics. The present results are obtained from configuration interaction atomic structure calculations using the code SUPERSTRUCTURE (SS) which includes relativistic effects in Breit-Pauli approximation. The comparison of the present energies with the available observed energies displayed very good agreement (\ 1%). The presented excitation energy results have been compared with other detailed relativistic approaches such as Dirac-Fock, coupled cluster and configuration interaction for a few ionic states.
Physical Review A - PHYS REV A, 1990
We present accurate calculations of the 1s22s and 1s22p energy levels of lithiumlike ions for 15<=2Z<=92. The multiconfiguration Dirac-Fock method has been used to calculate relativistic effects. One-electron radiative corrections and estimated screening corrections have been calculated. These results are in good agreement with relativistic many-body calculations. General agreement with experimental transition energies (available up to Z=92) is very good.
International Journal of Quantum Chemistry, 2005
On the basis of numerical, ab initio ⌬DF and ⌬HF computations of 1s-core, 2s-core, and 2p-core ionization energies of atoms, from Li through Xe, an allometric empirical formula that was proposed for evaluating relativistic corrections (including QED effects) to nonrelativistic values is assessed for homogeneous sets of elements in the periodic table. The two coefficients involved in this formula are precisely determined for 1s-core ionization in the sets of atoms Be-Ne, Mg-Ar, Zn-Kr, and Cd-Xe; 2s-core ionization in the sets of atoms Mg-Ar, Zn-Kr, and Cd-Xe; and 2p-core ionization in the set Mg-Ar. It is shown that the medium relative error on the results obtained using this formula, with respect to those directly computed, decreases from a few percent to a few hundredths of 1% when the depth of the ionized level increases. This formula could be used to include relativistic (and QED) corrections to results yielded by simpler, nonrelativistic calculations on complex molecules involving heavy atoms.
Physical Review A, 2009
Very accurate variational calculations of the fundamental pure vibrational transitions of the 3 He 4 He + and 7 LiH + ions are performed within the framework that does not assume the Born-Oppenheimer ͑BO͒ approximation. The non-BO wave functions expanded in terms of one-center explicitly correlated Gaussian functions multiplied by even powers of the internuclear distance are used to calculate the leading relativistic corrections. Up to 10 000 Gaussian functions are used for each state. It is shown that the experimental 3 He 4 He + fundamental transitions is reproduced within 0.06 cm −1 by the calculations. A similar precision is expected for the calculated, but still unmeasured, fundamental transition of 7 LiH +. Thus, three-electron diatomic systems are calculated with a similar accuracy as two-electron systems.
Atomic Data and Nuclear Data Tables, 2008
A relativistic multi-configuration Dirac-Fock technique has been used for computing the transition wavelengths, transition probabilities, absorption oscillator strengths, and line strengths for the Ka and Kb line transitions of He-like to Ne-like molybdenum ions. The contributions from the Breit interaction, quantum electrodynamic corrections, and nuclear mass corrections to the initial and final levels have been taken into account. Transitions from the ground state to the n = 2 and 3 states of He-like and Li-like molybdenum have been calculated using two sets of configuration-interaction wavefunctions. One set of wavefunctions was generated using the fully relativistic GRASPVU code and the other was obtained using GRASP 2 , the calculated transition wavelength, transition probabilities, and absorption strengths obtained by these two independent methods are in very good agreement and there is good agreement between these results and recent theoretical and experimental results. These data provide reference values for the level lifetimes, charge state distributions, and average charge of molybdenum plasmas.